The present invention relates to a wrench torque value calibrating apparatus, and more particularly to such a wrench torque value calibrating apparatus which is durable and precise, and practical for fine calibration adjustment.
The torque value of a torque wrench must be precisely calibrated, so as to prevent a damage to the workpiece. FIG. 1 shows a wrench torgue value calibrating apparatus according to the prior art. This structure of wrench torque value calibrating apparatus comprises a casing having a fixed block longitudinally disposed on a bottom wall of a top side thereof, an actuating member revolvably supported on the casing and having two polygonal end blocks at two opposite ends respectively extended out of two opposite lateral sides of the casing for turning with the torque wrench to be calibrated, a sliding block coupled to the fixed block and moved longitudinally along it, a flexible main rod having a first end perpendicularly connected to the actuating member and a second end stopped below the sliding block, and a torque meter mounted on the casing and having a probe perpendicularly disposed in contact with the flexible main rod. The flexible main rod is bent in one direction to lift the probe when the actuating member is turned with the wrench to be calibrated, thereby causing the torque meter to show the set torque value of the wrench to be calibrated. This structure of wrench torque value calibrating apparatus is not a high presicion calibrating instrument because it has no means for fine calibration adjustment. Another drawback of this structure of wrench torque value calibrating apparatus is its short service lile because the flexible main rod wears quickly with use.
The present invention has been accomplished to provide a wrench torque value calibrating apparatus which eliminates the aforesaid drawbacks. It is one object of the present invention to provide a wrench torque value calibrating apparatus which is practical for a fine calibration adjustment to achieve high precision. It is another object of the present invention to provide a wrench torque value calibrating apparatus which is durable in use. According to one aspect of the present invention, the wrench torque value calibrating apparatus comprises a casing having a fixed block longitudinally disposed on a bottom wall of its top side, an actuating member revolvably supported on the casing and having at least one polygonal end block extended out of the casing for turning with the torque wrench to be calibrated, a sliding block coupled to the fixed block of the casing and moved longitudinally along it, the sliding block having a top side coupled to the fixed block and a bottom side mounted with a roller, a flexible main rod having a first end perpendicularly connected to the actuating member and a second end stopped below the roller of the sliding block, and a torque meter mounted on the casing and having a probe perpendicularly disposed in contact with the flexible main rod, the flexible main rod being bent in one direction to lift the probe when the actuating member is turned with the wrench to be calibrated, causing the torque meter to show the set torque value of the wrench to be calibrated, wherein at least one auxiliary fixed block is longitudinally mounted inside the casing; at least one auxiliary sliding block is respectively coupled to the at least one auxiliary fixed block inside the casing, each of the at least one auxiliary sliding block having a top side coupled to the corresponding auxiliary fixed block and a bottom side mounted with a roller; at least one adjustment screw rod is mounted in a respective hole on the casing and respectively connected to the at least one auxiliary sliding block by a screw joint, the at least one adjustment screw rod being turned to move the at least one auxiliary sliding block along the at least one auxiliary fixed block respectively; and at least one flexible auxiliary rod is mounted inside the casing in parallel to the flexible main rod and coupled to the actuating member, the at least one flexible auxiliary rod having a greater flexibility than the flexible main rod, each of the at least one flexible auxiliary rod having a first end perpendicularly connected to the actuating member and a second end stopped below the roller of one auxiliary sliding block. According to another aspect of the present invention spring members are respectively mounted inside the casing to impart an upward pressure to the second ends of the flexible main rod and the at least one flexible auxiliary rod. According to still another aspect of the present invention, at least one spring holder is mounted inside the casing below the at least one flexible auxiliary rod, and at least one heavy-duty spring is respectively coupled between the at least one spring holder and the at least one flexible auxiliary rod and moved between the at least one auxiliary sliding block and the probe of said torque meter, the at least one heavy-duty spring imparting a downward pressure to the second end of each of the at least one flexible auxiliary rod.